In the master's thesis we created a concentration gradient in the flow-injection system by using two syringe-based pumps. Such pumps enable functions, which helped us to set programs to achieve a linear and exponential gradient profile. Flow rate of the first pump increased linearly/exponentially from zero to maximum value, while on the second pump flow rate decreased linearly/exponentially from maximum value to zero. Suitability of the set programs was checked firstly by pushing water through the system and secondly by pushing two dyes with different absorption maximum. Accordingly, we defined the conditions for titration. Reactions are controlled by gradient mode in flow analysis. The model titration which we monitored spectrometrically was the Cu(II)-EDTA disodium salt solution reaction producing a blue-colored product that absorbs more light than the solution of Cu(II). The titration results depend on the concentration range of the analytes and the ratios with the titrant that are formed in the flow by different gradient modes. We confirmed the shape differences in FIA-grams obtained for different concentrations of Cu(II) using exponential/linear gradient program. We further performed a gradient titration of Cu(II) with EDTA disodium salt solution in two different ways. First, Cu(II) and EDTA disodium salt solution were pushed alternately and second, Cu(II) was pushed into the continuous flow of EDTA disodium salt solution. In the first case we came to the conclusion that maximum of the curve for the product is shifted towards later times with increase in volume of Cu(II), in contrast to the second case, in which the maximum rises while the shape of the curve changes.
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